Conventional hot or cold beverage dispensing systems are widely used in offices, convenience stores, restaurants, homes, etc.
One type of widely used beverage dispenser system uses an impeller, such as blades, disc, etc., driven in rotation by an electric motor that mixes powder such as coffee or tea powder or syrup with a hot or cold liquid such as liquid in a whipping bowl or chamber before being dispensed in a cup. A system of this type is described for example in U.S. Pat. No. 4,676,401.
Systems of this type are sometimes expensive and cumbersome as a space is required for a mixing bowl or whipper-chamber and impeller engine. Further, in order to avoid hygienic issues, due to residual product left in the whipper-chamber and/or on the impeller, these systems require certain maintenance and periodic cleanings. Moreover, when using powders, precipitation of non-dissolved powder particles as well as stratification of liquids in a cup after dispensing may occur, especially at ambient temperature. “Stratification” in this usage refers to the amount of heterogeneity at different levels in the liquid part of the product.
Another type of system for producing and dispensing whipped soft drinks, such as hot chocolate and beverages, without using a mechanical whipping mechanism, such as rotating blades, has been proposed in U.S. Pat. No. 6,305,269. In this system, the whipping of the mixture of syrup and water used to produce the beverage is achieved by intermixing, within a vented mixing chamber, intersecting streams of syrup and water that are directed toward an intersection point under pressure. Even though this system eliminates the use of an impeller in the mixing chamber, the wall of the mixing chamber after it has been used becomes quickly soiled by residues so the hygiene is still an issue and periodical cleaning of the mixing chamber is still required. As the cleaning operations often require the mixing chamber to be removed they are labour-intensive and costly. Moreover, it has been shown that the foam obtained with this system using one water jet and one concentrate jet typically had a soapy appearance with large bubble size, and stability was extremely poor.
An improved system is needed that is better suited for producing certain products, such as cappuccino-type beverages, with an optimal foam layer, and that preferably can reduce cleaning required.